function [Tech,TechIndex] = TechIntroduce(Tech)
if all(Tech(:,3)==1)
    TechIndex=NaN;
else
    NeedNum = zeros(1,4);
    NeedPro = cell(1,4);
    for TechType=1:4
        allPro = Tech(find(Tech(:,1)==TechType),2:3);
        Need = abs(allPro(:,1).*(allPro(:,2)-1));
        Need(find(Need==0))=[];
        NeedPro{TechType} = Need;
        NeedNum(TechType) = length(Need);
    end
    [~,p] = max(NeedNum);
    TechIndex = NeedPro{p}(1);
    Tech(TechIndex,3)=1;
end
end